Hongo and Ichimonji's meeting is different from the series, in which Kamen Rider 1 rescues Ichimonji from Shocker, but here they have already met before becoming Riders.
The Rider's method of transforming is different from those used during the series.
Hideyo Amamoto (Dr. Shinigami) only appears through stock footage from previous Kamen Rider series. Amamoto passed away in 2003, 2 years before the film was made. Shinigami's voice is provided by Eiji Maruyama.
Hibiki's car is clearly a Toyota Yaris but it has a different badge on the front.